cum near lvagina lips

s.o noticed a cum on my vagina lip (pubic hair area) a tiny liquid. we were using condoms and when he was taking it off half of it was still inside me, he got it out immediately though (not even a second there) im not 101% worried but im not sure if its mine or his. He said he did not even wait for it to leak so its impossible its his. Should I take plan b? I'm a 11 days away from my period.